Animation retargeting is a popular research field that has progressed far beyond "bones with the same name". Review scientific literature to gather a lot of good ideas to try.

Lorenzo is right, but if you don't have the time or energy to read the latest research papers (which use a highly stylized math form), one thing you could try is affinitize the guest skeleton's bones to the host skeleton by transforming both skeletons into the same local space and then connecting guest bones to nearest neighbor skeleton bones using something like:

[Source]

for (DWORD i = 0; i < pSkin->m_numOffsetMatrices; i++)

{

D3DXVECTOR3 SkinPos( 0.0f, 0.0f, 0.0f );

D3DXMATRIX boneOffsetToRoot;

D3DXMatrixInverse( &boneOffsetToRoot, NULL, &pSkin->m_boneOffsetTransforms[ i ] );

D3DXVec3TransformCoord( &SkinPos, &SkinPos, &boneOffsetToRoot );

float bestDist = INFINITY;

for (DWORD j = 0; j < pSkeleton->m_numFrames; j++)

{

D3DXVECTOR3 BindPos( 0.0f, 0.0f, 0.0f );

D3DXVec3TransformCoord(

&BindPos,

&BindPos,

&pSkeleton->m_matrixFrames[ j ].

m_skeletalRootSpace );

float dist = D3DXVec3Length( &D3DXVECTOR3( SkinPos - BindPos ) );

if (dist < bestDist)

{

bestDist = dist;

pSkin->m_boneIndex[ i ] = j;

}

}

}

[/Source]